NEUTRON CRYSTAL-FIELD SPECTROSCOPY OF RNI(2)(11)B(2)C (R=HO, ER, TM)

Inelastic neutron scattering experiments of the crystal-field (CEF) sp litting of the R(3+) ions (R = Ho, Er, Tm) in the superconductor RNi(2 )(11)B(2)C have been performed in the paramagnetic as well as in the m agnetically ordered state in order to deduce the CEF parameters which in turn determine the thermodynamic magnetic properties of these syste ms. The calculated ordered magnetic moments are in agreement with magn etic neutron diffraction results, i.e. both the easy axis and the size of the zero-field moments are correctly reproduced. In addition, the entropy involved in the magnetic ordering obtained from specific heat measurements is in correspondence with the number of low-lying CEF sta tes observed in this study. Our CEF parameter set also reproduces both the behavior and the anisotropy in M/H measured for single crystals.